如何處理透過檔案探索工具開啟的檔案

寮國
Paances Liao

新穎時尚

使用 File Handling API

首先，請在網頁應用程式資訊清單中宣告 file_handlers 屬性。File Handling API 要求您必須指定 action 屬性 (處理網址) 和 accept 屬性，這是以 MIME 類型表示的物件和陣列，其中具有特別對應副檔名的鍵和陣列。

{
  "file_handlers": [
    {
      "action": "./",
      "accept": {
        "image/*": [".jpg", ".jpeg", ".png", ".webp", ".svg"]
      }
    }
  ]
}

接下來，您需要使用 File Handling API 透過 launchQueue 強制處理已開啟的檔案。

if ('launchQueue' in window && 'files' in LaunchParams.prototype) {
  launchQueue.setConsumer((launchParams) => {
    if (!launchParams.files.length) {
      return;
    }
    for (const fileHandle of launchParams.files) {
      // Handle the file.
    }
  });
}

瀏覽器支援

  • 102
  • 102
  • x
  • x

經典風格

使用傳統版 DataTransferItem.getAsFile() 方法

如果不支援 File Handling API，您仍可從檔案探索工具將檔案拖曳到應用程式中。DataTransferItem.getAsFile() 方法會傳回拖曳資料項目的 File 物件。如果項目不是檔案，此方法會傳回 null。雖然您可以讀取檔案，但無法寫回檔案。這種方法的缺點是不支援目錄。

瀏覽器支援

  • 11
  • 12
  • 50
  • 5.1

資料來源

漸進增強

下方的程式碼片段會在檔案處理時使用 File Handling API，並額外註冊拖曳處理常式，以便處理拖曳的檔案。

宣告可在網頁應用程式資訊清單中處理的檔案類型。瀏覽器如果不支援 File Handling API，則會忽略此 API。

{
  "file_handlers": [
    {
      "action": "./",
      "accept": {
        "image/*": [".jpg", ".jpeg", ".png", ".webp", ".svg"]
      }
    }
  ]
}

// File Handling API
const handleLaunchFiles = () => {
  window.launchQueue.setConsumer((launchParams) => {
    if (!launchParams.files.length) {
      return;
    }
    launchParams.files.forEach(async (handle) => {
      const file = await handle.getFile();
      console.log(`File: ${file.name}`);
      // Do something with the file.
    });
  });
};

if ('launchQueue' in window && 'files' in LaunchParams.prototype) {
  handleLaunchFiles();
}

// This is the drag and drop zone.
const elem = document.querySelector('main');
// Prevent navigation.
elem.addEventListener('dragover', (e) => {
  e.preventDefault();
});
// Visually highlight the drop zone.
elem.addEventListener('dragenter', (e) => {
  elem.style.outline = 'solid red 1px';
});
// Visually unhighlight the drop zone.
elem.addEventListener('dragleave', (e) => {
  elem.style.outline = '';
});
// This is where the drop is handled.
elem.addEventListener('drop', async (e) => {
  // Prevent navigation.
  e.preventDefault();
  // Unhighlight the drop zone.
  elem.style.outline = '';
  // Prepare an array of promises…
  const fileHandlesPromises = [...e.dataTransfer.items]
    // …by including only files (where file misleadingly means actual file _or_
    // directory)…
    .filter((item) => item.kind === 'file')
    // …and, depending on previous feature detection…
    .map((item) => item.getAsFile());
  // Loop over the array of promises.
  for await (const handle of fileHandlesPromises) {
    // This is where we can actually exclusively act on the files.
    if (handle.isFile) {
      console.log(`File: ${handle.name}`);
      // Do something with the file.
    }
  }
});

其他資訊

示範

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link rel="manifest" href="manifest.json" />
    <title>How to handle files opened from the file explorer</title>
    <link rel="stylesheet" href="style.css" />
    <!-- TODO: Devsite - Removed inline handlers -->
    <!-- <script>
      if ('serviceWorker' in navigator) {
        window.addEventListener('load', async () => {
          const registration = await navigator.serviceWorker.register(
            'sw.js',
          );
          console.log(
            'Service worker registered for scope',
            registration.scope,
          );
        });
      }
    </script>
    <script src="script.js" type="module"></script> -->
  </head>
  <body>
    <h1>How to handle files opened from the file explorer</h1>
    <p>Install the app. After the installation, try opening an image file from the file explorer with the app.
  </body>
</html>

CSS


        html {
  box-sizing: border-box;
  font-family: system-ui, sans-serif;
  color-scheme: dark light;
}

*, *:before, *:after {
  box-sizing: inherit;
}

body {
  margin: 1rem;
}

img {
  height: auto;
  max-width: 100%;
  display: block;
}

JS


        if ('launchQueue' in window && 'files' in LaunchParams.prototype) {
  launchQueue.setConsumer((launchParams) => {
    if (!launchParams.files.length) {
      return;
    }
    for (const fileHandle of launchParams.files) {
      document.body.innerHTML += `
${fileHandle.name}
`;
    }
  });
}